January 28, 2012

"We have cracked open the door to what is possible for life elsewhere in the universe," Felisa Wolfe-Simon of the NASA Astrobiology Institute and U.S. Geological Survey, who led the NASA Mono Lake study.

Rosie Redfield of the University of British Columbia has steadfastly raised doubts about the headline-grabbing news about arsenic-based life discovery at Mono Lake in November 2010. Redfield then she set out to replicate the initial findings, getting the original bacteria and seeing whether they can build DNA from arsenic when deprived of phosphorus. She then started to chronicle her experiences on her blog.

Among other things, Redfield reports that the bacteria seem to be able to grow at very low levels of phosphorus–levels that the original scientists claimed were too low to sustain the growth they saw.

Fast forward to 2012, a group of scientists, led by Redfield have posted data on Redfield's blog that, she says, present a "clear refutation" of key findings from the paper. But after Redfield and others raised numerous concerns, many of which were published as technical comments in Science, Redfield put the results to the test, documenting her progress on her blog to advance the cause of open science .

Redfield and her collaborators hope to submit their work to Science by the end of the month. She says that if Science refuses to publish the work because it has been discussed on blogs, it will become an important test case for open science."

When NASA announced the discovery of an arsenic-eating microbe in a California lake, the agency hailed it as a suggestion that there are lifeforms beyond our current DNA-based model as we know it. Every living thing that scientists have ever studied uses phosphorus to build the backbone of its DNA. The NASA-funded scientists described a microbe that could use arsenic instead. If the authors of the paper were proved right, we would have to expand our notions of what forms life can take.

NASA's team of astrobiologists had taken samples of the bacteria from ancient Lake Mono, located in a volcanic region of Northern California near the Nevada border, and starved them of phosphate, the mineral of choice for most DNA-based organisms. Instead, the scientists force-fed the bacteria a form of arsenic, and, much to the researchers' delight, the bacteria continued to grow and flourish on their new diet of poison.

But then other scientists began their standard peer review process and dug into the details outlining NASA's research and findings, and they're now two years later, charging that the research behind it is seriously flawed.

"I was outraged at how bad the science was," Redfield said in an interview with Slate's Carl Zimmer back in 2011. Redfield also posted a scathing critique of the report on her blog.

Redfield and other scientists point out that when NASA scientists removed the DNA from the bacteria for examination, they didn't take the steps necessary to wash away other types of molecules, which means, that the arsenic may have merely piggybacked onto the bacteria's DNA without becoming truly absorbed into it.

The report's detractors also note that the NASA scientists fed the bacteria salts that contained trace amounts of phosphate, so it's possible that the bacteria were able to survive on those tiny helpings of phosphate instead of the arsenic.

"This paper should not have been published," University of Colorado molecular biology professor Shelley Copley told Slate's Zimmer.

"I suspect that NASA may be so desperate for a positive story that they didn't look for any serious advice from DNA or even microbiology people," UC-Davis biology professor John Roth told Zimmer.

The NASA paper's authors have not responded to the firestorm, provoking additional criticism: "That's kind of sleazy given how they cooperated with all the media hype before the paper was published," Redfield said soon after thev discovery was announced.

Comments

Well what if it had 5 billion years say? And would it be DNA that would be changed? Say it turns into something like DNA but with an arsenic background instead of phosphate. Just wondering if it is still plausible.